1. Field of the Invention
The present invention generally relates to apparatus and methods for mounting optical components.
2. Description of the Related Art
The manufacturing processes involved in generating optical systems generally requires precise alignment of lenses, prisms, mirrors, isolators, and other optical components within various mounting apparatuses. Precise alignment is particularly important in laser-based optical systems, as misalignment may interfere with optical isolation, which may reduce or eliminate the optical gain needed for proper laser operation and may increase system noise. Additionally, with regard to polarization and filtration processes involving crystals, the crystals often require precise alignment in order to achieve minimum insertion loss and maximum polarization parameters. Although optical isolators often use magnets to align the photons for increased polarization efficiency with respect to the crystal lattice, if the magnets are not properly aligned relative the lattice, polarization may nonetheless still be negatively affected and the return loss decreased.
Therefore, in order to minimize component alignment problems, specialized optical mounting devices are frequently used to secure optical components therein. For example, a retainer ring, spring-type retainer, or other means for exerting a biasing/securing pressure generally operates to secure the optical component within the mounting device, thereby reducing the chance that the optical component will be moved out of alignment after the initial assembly process is complete. It is desirable to apply the biasing pressure in a single direction, i.e., the component is preferably biased against a fixed member in a unitary direction in order to prevent translational movement of the component. However, conventional configurations may still be subject to small perturbations in directions other than the biasing pressure direction, such as, for example, in a rotational direction or a direction orthogonal to the biasing direction. For example, many optical mounts (especially prism mounts) make use of a spring retainer, wherein the spring retainer contacts the top of the optical component urging it down against a base plate. In this configuration, the optical component is prevented from being translated in the direction of the biasing force, however, rotational movement and/or slipping of the lens horizontally is not restricted. Conversely, many optical isolator mounts secure their optical components at their perimeter, thereby preventing rotation, however, these mounting configurations may still be susceptible to translational movement or slippage. Another common optical component mounting technique is to clamp the optical component in place with a rod that urges the optical component against one or more base plates, where the rod is attached to a post with locking screws, and the rod in turn is securely attached to the base plates. However, the use of screws can be problematic, as they may loosen in time, particularly when they are exposed to the temperature cycling that often accompanies optical systems. Furthermore, the rod configuration generally offers only a unitary direction biasing/securing force, and therefore, it is again susceptible to rotational and horizontal translations.
Another common approach to mounting optical components is to use epoxy-based mounts. In these configurations, the optical component is placed in a mount and an epoxy is applied to the perimeter of the component. Once the epoxy cures, the component is generally affixed in the mount and is not susceptible to movement. However, although the use of epoxies is generally suitable for room temperature applications, epoxy mounts have shown weakness in environments where the temperature fluctuates, as epoxies and optical materials generally have different temperature coefficients of expansion. Thus, the epoxy may expand or contract at a different rate than the surrounding mount or the optical component itself, which can displace the optical component and potentially break the mounting bond.
Therefore, in view of the disadvantages of conventional optical mounting devices and methods, there is a need for a simple, easily manufactured, efficient, and cost effective optical component mounting apparatus that overcomes the disadvantages of conventional optical mounting devices.